GI viruses Flashcards
List two groups of viruses that infect the GI tract
Enteroviruses- do not cause diarrhea
Viruses with the primary symptom of diarrhea
List the four groups that comprise the enteroviruses
Polioviruses
enteroviruses
coxackie viruses
echoviruses
Enteroviruses are shed in large numbers in the feces, are acid stable, and resist _____
alcohols and detergents
List six syndromes that are consistently present in enterovirus infection
Rash (all except polio) aseptic meningitis pericarditis/ myocarditis paralysis hepatitis colds
What type of virus is most stronly associated with myocarditis
coxackie viruses
A high percentage of enterovirus infections are _____ especially in children
asymptomatic
Diagnosis of enterovirus is primarily based on:
clinical presentation- many strains, so specific testing is limited AND there are no specific therapies so identifying the specific virus is not useful
True or false: there are no antivirals available for enteroviruses
True
What is the best approach to treating enteroviruses?
- start with prevention- hand hygiene, food handling
- vaccines for hepatitis A and polio virus
- mostly self limited illnesses, supportive care as necessary
How is polio virus transmitted?
Fecal-oral route, replicates in gut mucosa.
Enters through Peyer’s patches and M cells in the gut
For all members of the enterovirus, CNS disease requires ______ and _______
high viral titers
persistent secondary viremias
What causes paralysis in polio infection?
Viral replication in and killing motor neurons of the anterior horn of the spinal column
Describe post-polio syndrome:
nervous system recovers in young people so mild paralytic damage is “masked”
as people age, they become less able to compensate for CNS damage and the original paralytic symptoms return
NOT due to return of polio virus
List families of viruses associated with diarrhea
Major: rotavirus, norovirus, astrovirus
Some serotypes of adenovirus and coronavirus
Describe the transmission of viruses that cause diarrhea
transmitted by the fecal-oral route, are very stable, are acid resistant, and large amounts of
virus are shed in stools
True or false: shedding of virus stops as soon as diarrhea symptoms subside
False, continued shedding for extended periods of time
In the US, rotavirus has a seasonal peak in the _____
winter
True or false: most people are seropositive for rotavirus by age 4
true, 90%
Describe the clinical syndrome of rotavirus infection
1-3 day incubation periods
abrupt onset of watery stools that become clear as colonic material is flushed out
fever is possible but would be mild
usually self limiting, high mortality in resource poor areas due to dehydration
What tests exist to diagnose rotavirus infection
electron microscopy
ELISA antigen capture assay that uses stool samples
** no antivirals, so usually make dx based on season, pt age, clinical presentation
What is the best strategy for preventing rotavirus infection?
Live attenuated vaccine
Safe food and water supplies
Describe the epidemiology of norovirus
No seasonality
extremely contagious- outbreaks in schools, institutional settings, cruise ships high rates of infection in household contacts
thought to be the cause of 30% of gastroenteritis in older children and adults
Describe the clinical syndrome of norovirus
Abrupt onset of diarrhea, nausea, vomiting, abdominal cramps
Self limiting, resolves within 24-48 hours
Describe the transmission of norovirus
fecal-oral route, via contaminated food or water
How is diagnosis of norovirus made?
Clinical presentation
Public health my follow local outbreaks
No culture, possible but not practical to do electron microscopy, RT-PCR
- no antivirals so therapeutic focus is on avoiding dehydration
Describe the epidemiology of astroviruses
Common cause of viral gastroenteritis
75% of children 4 years old are seropositive
Describe the clinical presentation of astrovirus
3-4 day incubation then diarrhea, nausea, headache, malaise for 2-4 days.
Vomiting can occur but not as common as in norovirus
Fever is not common
How is diagnosis of astrovirus made?
Symptoms and age of patient
No culture, possible to do electron microscopy on stool but not practical
NO vaccines or antivirals
What is the best way to prevent astrovirus infection?
hand washing, good hygiene, proper food handling and preparation procedures,
and clean water supplies.
Describe symptoms seen in adenovirus gastroenteritis
Short incubation period
Acute onset of diarrhea, nausea, occasionally vomiting, possible low grade fever
What strains of adenovirus cause GI illness?
40,41, 38
Gastroenteritis caused by coronavirus is most commonly seen in ________
children, under 1 yr of age
Describe the clinical presentation of coronavirus
Gastroenteritis is diarrhea that has occult blood, is less water and more mucoid
coronavirus also causes colds, SARS
Of all the viruses that cause diarrhea there is a vaccine for only one:
rotavirus
Describe current thinking on why enterovirus does not cause diarrhea but other gastroenteric viruses do
Structural protein of rotavirus acts similarly to cholera toxin, there is a capsid protein on astrovirus that is a toxin that disrupts actin filaments, coronavirus causes inflammation that leads to the occult blood and mucus in the stool
thought that other enteric viruses might have toxic activity
